Question

Q. Chits numbered from 1 to 20 are kept in a box and mixed thoroughly. one is drawn at random from the box.Find the probability of that the number on the sheet is (1)an odd number (2) a prime number (3)a multiple of 5 ​

Answer 1

Answer:

Odds of drawing an ODD NUMBER

There are 10 odd numbers from 1 to 20. So,

Odds = 10/20

Simplification

10/20

(Cutting of Zeros)

1/2

Odds = 1/2

Odds of drawing a PRIME NUMBER

There are 8 prime numbers from 1 to 20. So,

Odds = 8/20

Simplification

8/20

(Cutting with 2)

4/10

(Cutting with 2)

2/5

Odds = 2/5

Odds of drawing a MULTIPLE OF 5

There are 4 multiples of 5 from 1 to 20. So,

Odds = 4/20

Simplification

4/20

(Cutting with 2)

2/10

(Cutting with 2)

1/5

Odds = 1/5

Answer 2

Step-by-step explanation:

Solution(i):

Let E be event of drawing a card with number divisible by 2 or 3 from the cards with numbers 1 to 20

Numbers divisible by 2 or 3 from 1 to 20=2,3,4,6,8,9,10,12,14,15,16,18,20

No. of favorable outcomes=13

Total no. of possible outcomes =20

We know that, Probability P(E) =(Total no.of possible outcomes)(No.of favorable outcomes)=2013

Therefore, the probability that a number on the card selected from numbers 1 to 20 divisible by 2 and 3 is 2013

Solution(ii):

Let F be event of drawing a card with prime number from the cards with numbers 1 to 20

Prime numbers from 1 to 20=2,3,5,7,11,13,17,19

No. of favorable outcomes=8

Total no. of possible outcomes =20

We know that, Probability P(F) =(Total no.of possible outcomes)(No.of favorable outcomes)=208=52

Therefore, the probability that a card with prime number is selected from numbers 1,2,3,...,20  =52